Final answer:
The patient's statement "I feel like someone is pounding nails into my head" would be documented in the SOAP format under the subjective section.
Step-by-step explanation:
In the SOAP format, the patient's statement "I feel like someone is pounding nails into my head" would be documented under the S section, which stands for subjective. This section of the SOAP note includes the patient's chief complaint and subjective symptoms that the patient reports. The statement about the pounding nails sensation would be recorded as part of the patient's subjective experience of their symptoms.